kvm with usb slow

kvm with usb slow

[Norbert Preining]

Hi all,

(please Cc, thanks)

I am running kernel 2.6.24-rc6 and kvm-56 (or was it 55) and as soon as
I plug an usb device with usb enabled it is getting terrible slow. I
have searched a bit and it seems to be related to async i/o not being
implemented. 

Is this expected behaviour, and if yes, are there patches floating around
for testing?

Best wishes

Norbert

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Dr. Norbert Preining <preining-DX+603jRYB8@public.gmane.org>        Vienna University of Technology
Debian Developer <preining-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>                         Debian TeX Group
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Re: kvm with usb slow

[Dor Laor]

[-- Attachment #1.1: Type: text/plain, Size: 1687 bytes --]

Norbert Preining wrote:
>
> Hi all,
>
> (please Cc, thanks)
>
> I am running kernel 2.6.24-rc6 and kvm-56 (or was it 55) and as soon as
> I plug an usb device with usb enabled it is getting terrible slow. I
> have searched a bit and it seems to be related to async i/o not being
> implemented.
>
Can you please tell the device type, is it usb2.0 or usb1.1 ?
Is running with -no-kvm improve something?
>
> Is this expected behaviour, and if yes, are there patches floating around
> for testing?
>
Arnon will send updated patches soon.
>
> Best wishes
>
> Norbert
>
> -------------------------------------------------------------------------------
> Dr. Norbert Preining <preining-DX+603jRYB8@public.gmane.org>        Vienna University of 
> Technology
> Debian Developer <preining-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>                         Debian 
> TeX Group
> gpg DSA: 0x09C5B094      fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 
> 09C5 B094
> -------------------------------------------------------------------------------
> HASTINGS (pl.n.)
> Things said on the spur of the moment to explain to someone who comes
> into a room unexpectedly precisely what it is you are doing.
>                         --- Douglas Adams, The Meaning of Liff
>
> -------------------------------------------------------------------------
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Re: kvm with usb slow

[Arnon Gilboa]

USB redirection support in qemu  is currently using synchronous ioctls,
which might block the guest for too long (>100usec). The current host
controller emulations allow only one pending transfer at a time, which
might slow down the guest as well.

If you are using simple bulk device (disk on key, printer etc.), you can
try the patch of USB 2.0 EHCI emulation, recently submitted to
qemu-devel. It is at very preliminary stage, but still might be useful
for you.

Arnon
-----Original Message-----
From: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
[mailto:kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org] On Behalf Of Norbert
Preining
Sent: Sunday, January 06, 2008 6:42 PM
To: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: [kvm-devel] kvm with usb slow

Hi all,

(please Cc, thanks)

I am running kernel 2.6.24-rc6 and kvm-56 (or was it 55) and as soon as
I plug an usb device with usb enabled it is getting terrible slow. I
have searched a bit and it seems to be related to async i/o not being
implemented. 

Is this expected behaviour, and if yes, are there patches floating
around for testing?

Best wishes

Norbert

------------------------------------------------------------------------
-------
Dr. Norbert Preining <preining-DX+603jRYB8@public.gmane.org>        Vienna University of
Technology
Debian Developer <preining-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>                         Debian
TeX Group
gpg DSA: 0x09C5B094      fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3
09C5 B094
------------------------------------------------------------------------
-------
HASTINGS (pl.n.)
Things said on the spur of the moment to explain to someone who comes
into a room unexpectedly precisely what it is you are doing.
			--- Douglas Adams, The Meaning of Liff

------------------------------------------------------------------------
-
This SF.net email is sponsored by: Microsoft Defy all challenges.
Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
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Re: kvm with usb slow

[Norbert Preining]

Hi Arnon,

thanks a lot for the response,

On Mo, 07 Jan 2008, Arnon Gilboa wrote:
> USB redirection support in qemu  is currently using synchronous ioctls,
> which might block the guest for too long (>100usec). The current host
> controller emulations allow only one pending transfer at a time, which
> might slow down the guest as well.

Ok, I understand. So anything which is a bit complicated usb device
(like my GPS receiver) will have problems.

> If you are using simple bulk device (disk on key, printer etc.), you can
> try the patch of USB 2.0 EHCI emulation, recently submitted to
> qemu-devel. It is at very preliminary stage, but still might be useful
> for you.

I will try (to find and use it).

Thanks a lot and all the best

Norbert

-------------------------------------------------------------------------------
Dr. Norbert Preining <preining-DX+603jRYB8@public.gmane.org>        Vienna University of Technology
Debian Developer <preining-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org>                         Debian TeX Group
gpg DSA: 0x09C5B094      fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
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